Currant Aphides. 



307 



bunches " shanking " in consequence of the abnormal 

 presence of these pests. The rapid increase of the " Plant 

 Lice" was due to the long spell of dry, warm weather 

 so favourable to the development of these insects, so detri- 

 mental to the development of the fruit and health of the 

 bushes. Aphides are usually more or less prevalent on the 

 currants, and are always liable under certain climatic condi- 

 tions, such as existed during the past June, to increase to 

 an injurious extent. 



Currant bushes should therefore be washed early in the 

 year just as regularly as apple, plum, and pear trees. Four 

 species of Aphides, or Dolphins, occur on the three kinds of 

 currants, two are more or less confined to the currant and other 

 Ribes, namely, the Currant Blister Aphis (Rhopalostfihum 

 rib is of Linnaeus) and Myzus rib is of Linnaeus, the third 

 species found is the Cherry Aphis {Myzus cct asi, Fabricius), 

 and a fourth species is at present unidentified. 



The two true Ribes species work in a slightly different 

 way.- One, R. ribis, produces reddish, reddish-brown, or 

 yellow blister-like galls on the surface of the leaves, whilst 

 Myzus ribis often causes the leaves to curl up, especially on 

 the top shoots. Both species are equally difficult to destroy 

 after they commence to breed in numbers, owing to their 

 being hidden, and more or less protected in the hollows of 

 the blisters and under the curled-up leaves. The galled 

 patches are chiefly noticed on the upper surface of the leaf, 

 where they are blister-like ; below they are concave. In 

 this cavity the Aphides live and breed, increasing the area 

 of the disease patch as they develop. Numerous blisters 

 may be formed on one leaf, varying in size from one- 

 fourth to nearly an inch in length. Occasionally a moss- 

 like growth may be seen inside and outside these galls. 

 The leaves so attacked shrivel away, but the fruit often falls 

 owing to loss of sap long before the leaves die. Neither 

 of these Aphides form much " honey-dew " early in the year, 

 hence the diseased appearance of the leaf is often not noticed 

 as being of insect origin during the early stages of the 

 attack unless an examination has been made of the under 

 surface. The fruit has been particularly noticed to " run 



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